Emissions from polyurethane foam are a concern in many applications, especially when workers or end users are exposed to the foam within an enclosed space. Aldehyde emissions, such as formaldehyde, are a particular cause of concern. To reduce such aldehyde emissions, several methods have been developed to reduce the aldehyde content of the raw materials used in producing polyurethane foam. For example: U.S. Pat. No. 7,879,928 discloses a method for preventing the formation of aldehyde compounds in polyether or polyester polyols by incorporating a phenolic antioxidant and an aminic antioxidant into the polyol; U.S. Pat. Publ. No. 2009/0227758 discloses a method of reducing aldehydes in polyols and polyisocyanates by reacting the polyol with an oxazolidine-forming amino alcohol and the polyisocyanate with a nitroalkane; and U.S. Pat. No. 5,506,329 discloses the use of certain aldimine oxazolidine compounds for scavenging formaldehyde from polyisocyanate-containing preparations.
In addition to polyols and polyisocyanates, amine catalysts are often utilized as a raw material in the production of polyurethane foam. The aldehydes found in amine catalysts may be derived from a variety of sources, for example, they may be present as a contaminant from the manufacture of the amine, or they may result from the oxidation or free radical attack of various carbon segments of the amine during storage. Methods to reduce the aldehyde content in amine catalysts include the use of inert gas (see U.S. Pat. Publ. No. 2013/0085193), primary amines (see U.S. Pat. Publ. No. 2011/0009513) free radical scavengers (see U.S. Pat. Publ. No. 2012/0271026) and combining an amine which has urea, amide, secondary-amine, primary amine or secondary-hydroxyl functionality with a carboxylic diacid or triacid (see U.S. Pat. Publ. No. 2013/0137787).
Despite the state of the art, there is a continuing need for developing other inexpensive and effective methods to reduce the aldehyde content in amine catalysts. Preferably, such methods do not result in significant changes in the properties or performance of the amine catalyst or the resulting polyurethane foam. Moreover, preferably such methods do not produce other fugitive species which may bring additional environmental, health and safety issues to the amine catalyst and resulting polyurethane foam.